CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Comprehensive Income (Loss) [Line Items]
Net income (loss)	$ 20.8	$ (32.2)	$ 70.5	$ (2.9)
Available-for-sale securities and derivative instruments:
Net appreciation during the period	26.6	35.4	90.2	35.6
Portion of other-than-temporary impairment losses transferred from other comprehensive income	2.7	2.1	7.3	5.4
Benefit (provision) for deferred income taxes	15.6	(1.6)	(8.7)	1.5
Other comprehensive income	44.9	35.9	88.8	42.5
Amortization recognized as net periodic benefit costs:
Net actuarial loss	3.3	3.8	6.5	7.7
Prior service cost	(1.0)	(1.3)	(1.9)	(2.6)
Total amortization recognized as net periodic benefit costs	2.3	2.5	4.6	5.1
Provision for deferred income taxes	(0.8)	(0.9)	(1.6)	(1.8)
Total pension and postretirement benefits	1.5	1.6	3.0	3.3
Cumulative foreign currency translation adjustment:
Amount recognized as cumulative foreign currency translation during the period	(12.9)		1.4
Benefit (provision) for deferred income taxes	4.5		(0.5)
Total cumulative foreign currency translation adjustment	(8.4)		0.9
Other comprehensive income	38.0	37.5	92.7	45.8
Comprehensive income	$ 58.8	$ 5.3	$ 163.2	$ 42.9